The surface components of gonococci (Gc) dictate this bacterium's pathogenic personality. Pili are thought to initiate and maintain adherence of Gc to a host mucosae, thereby promoting colonization and infection. This is correlated with virulence of pilus+ and avirulence of pilus- Gc in human volunteers. Previous work from this laboratory focused on structural variation among pili elaborated by Gc recovered from experimental human infections, both in terms of their antigenic diversity and the mechanisms responsible for such changes. Current work is directed toward illuminating similar questions agout another set of Gc surface components--the outer membrane protein II (P.II) family. When expressed, each P.II is a major component of the outer membrane, but production of these polypeptides has no known consequences for Gc cultivated in vitro. Experiments during the past year have concentrated on expression of Gc recovered form males that were experimentally infected with P.II- organisms. These input P.II- Gc were quickly replaced by P.II+ variants, and from this strain's repertoire of 12+ P.II species, P.IIc was dominant among reisolated organisms. In addition to this survey of P.II expression by infecting Gc, studies were conducted on the genetic control of these outer membrane polypeptides. Several P.II genes were cloned from a single strain and were then sequenced. In vitro mutagenesis was used to determine the mechanism by which P.II genes that are "out-of-frame" display low level expression in E. coli. Cloned P.II genes into which TnphoA has been inserted as reporter molecules were constructed to examine the processing and transport of protein II to the Gc outer membrane.